Scheme 9 from Empty Space

S9fES is a mature, portable, and comprehensible interpreter for the R4RS Scheme programming language. It offers the following features:

support for low-level Unix programming

cursor addressing with Curses

decimal-based real number arithmetics

basic networking procedures

loads of useful library functions

The S9fES code strives to be simple and comprehensible. It is written in ANSI C (C89) mixed with Scheme and runs in many popular environments, including *BSD, Linux, Plan 9, and Windows.

S9fES has been placed in the public domain by its author. Because the author did not host the code for a while in 2011 and may or may not host it at any given time, this mirror has been established. Check out the original site [1] to see the current status.

The internal structure of the interpreter is documented in detail in the book "Scheme 9 from Empty Space" [2]. An obsolete version of the book is available for free at [3].